US6973052B2 - Hybrid power save delivery method in a wireless local area network for real time communication - Google Patents

Hybrid power save delivery method in a wireless local area network for real time communication Download PDF

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Publication number
US6973052B2
US6973052B2 US10/741,659 US74165903A US6973052B2 US 6973052 B2 US6973052 B2 US 6973052B2 US 74165903 A US74165903 A US 74165903A US 6973052 B2 US6973052 B2 US 6973052B2
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Prior art keywords
mobile station
access point
data
wlan
frame
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US20050135302A1 (en
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Huai Y. Wang
Ye Chen
Stephen P. Emeott
Floyd D. Simpson
Timothy J. Wilson
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Motorola Solutions Inc
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Motorola Inc
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Priority to US10/741,659 priority Critical patent/US6973052B2/en
Assigned to MOTOROLA, INC. reassignment MOTOROLA, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHEN, YE, EMEOTT, STEPHEN P., WILSON, TIMOTHY J.
Priority to CN2004800379760A priority patent/CN1922895B/en
Priority to PCT/US2004/042325 priority patent/WO2005064952A1/en
Priority to JP2006545447A priority patent/JP4733052B2/en
Priority to CA2550399A priority patent/CA2550399C/en
Priority to BRPI0417842-4A priority patent/BRPI0417842A/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W52/00Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02Power saving arrangements
    • H04W52/0209Power saving arrangements in terminal devices
    • H04W52/0212Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0216Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02DCLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00Reducing energy consumption in communication networks
    • Y02D30/70Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This invention relates in general to wireless local area networks, and more particularly to power save methods for reducing power consumption at a mobile station while engaged in a time sensitive communication activity.
  • Wireless LAN (WLAN) systems providing broadband wireless access have experienced a spectacular rise in popularity in recent years. While the principal application of these systems has been in providing network connectivity to portable and mobile devices running data applications such as, for example, email and web browsing, there has been a tremendous and growing interest in supporting isochronous services such as telephony service and streaming video.
  • the 802.11 standard defines procedures which can be used to implement power management in a handheld device during periods of inactivity.
  • three distinct building blocks are provided to support power savings: a Wakeup Procedure, a Sleep Procedure, and a Power-save Poll (PS-Poll) Procedure.
  • PS-Poll Power-save Poll
  • a mobile client voice station mobile station
  • Wakeup Procedure There are generally two reasons for the mobile station to wake up, namely to transmit pending data or to retrieve buffered data from the fixed station serving the mobile station, known as an access point. Waking up to transmit data is a straightforward operation, driven by the mobile station. The decision to wake up and receive data is also made by the mobile station after monitoring its pending data bit in a periodic beacon frame transmitted by its access point. Once the mobile station decides to transition from sleep mode to active mode, it notifies the access point by sending an uplink frame with the power-save (PS) bit set to active. Following such transmission, the mobile station remains active so the access point can send any buffered downlink frames afterward.
  • PS power-save
  • a mobile station in the active mode needs to complete a successful mobile station-initiated frame exchange sequence with PS bit set to sleep to transition into the sleep mode. Following this frame exchange sequence, the access point buffers all the downlink frames to this mobile station.
  • a power-save mobile station can solicit an immediate delivery from its access point by using a PS-Poll frame.
  • the access point can immediately send one buffered downlink frame (immediate data response) or simply send an acknowledgement message and response with a data frame later (delayed data response).
  • immediate data response a mobile station can stay in sleep state after finishing this frame exchange since there is no need for the mobile station to transition to active state given that the access point can only send a buffered downlink frame after receiving a PS-poll from the mobile station.
  • the mobile station has to transition to the active state until receiving a downlink frame from the access point.
  • FIG. 1 The architecture of a simple enterprise WLAN system is depicted in FIG. 1 .
  • FIG. 1 there is shown a block system diagram overview 100 of a typical enterprise WLAN system. It includes an infrastructure access network 101 , consisting of an Access Point 102 and mobile stations such as a data stations 104 and a voice station 106 . The mobile stations are connected to the access point via a WLAN radio link 108 . The access point is wired to a distribution network, including voice and data gateways 110 , 112 respectively, through a switch 114 .
  • a distribution network including voice and data gateways 110 , 112 respectively, through a switch 114 .
  • the voice station runs a Voice-over-IP (VoIP) application, which establishes a peer-to-peer connection with the voice gateway, representing the other end of the voice call, and which routes voice data to a voice network 116 .
  • VoIP Voice-over-IP
  • Data stations may connect to the data gateway via the access network and connect to, for example, a wide area network 118 .
  • the impact of data traffic on voice quality should be considered. It is assumed that both the voice and data stations employ a prioritized contention-based quality of service mechanism.
  • VoIP traffic characteristics make voice over WLAN applications uniquely suited for power save operation.
  • VoIP applications periodically generate voice frames, where the inter-arrival time between frames depends upon the voice coder chosen for an application.
  • the process of encapsulating voice frames into IP packets is commonly referred to as packetization, which is often assumed to occur once every 20 millisecond.
  • a typical VoIP conversation involves a bi-directional constant bit rate flow of VoIP frames, including an uplink flow from the handset to a voice gateway and a downlink flow in the reverse direction.
  • the station Since the station generally knows in advance the frame arrival rate, delay, and bandwidth requirements of its voice application, it can reserve resources and set up power management for its voice flows in agreement with the access point.
  • a mobile station may forgo power save mode, and remain in active mode, always ready for the downlink voice transmission.
  • the access point may transmit downlink voice frames as they arrive.
  • the mobile station may employ the power save building blocks described previously to wake up, exchange the VoIP frame with its access point, and go back to sleep.
  • EDCA Enhanced Distributed Channel Access
  • CSMA/CA Carrier Sensing Multiple Access with Collision Avoidance
  • AIFS arbitration inter-frame space
  • CWmin Minimum contention window
  • CWmax Maximum contention window
  • EDCA provides prioritized access control by adjusting contention parameters: AIFS, CWmin, and CWmax.
  • the first prior art power management mechanism utilizes a bit in the packet header.
  • the bit is designated as a power management (PM) bit to signal the change of the power state of the mobile station to the access point.
  • PM power management
  • a mobile station transitions from sleep mode to active mode upon having an uplink data frame to transmit by setting the PM bit to active in an uplink voice frame to notify the change of its power state. Knowing that there will be one corresponding downlink frame buffered at the access point, because uplink and downlink vocoder share the same voice frame duration, the mobile station stays in active mode for the downlink transmission. After receiving the uplink transmission, the access point then sends buffered downlink frames to the mobile station.
  • the access point sets the “more data” bit to FALSE to communicate the end of the downlink transmission.
  • the mobile station needs to complete a successful station-initiated frame exchange sequence with PM bit set to sleep to transition into the sleep mode. (e.g. an uplink frame, or a Null frame if there is no uplink data frame to transmit, with the PM bit set to sleep).
  • PM bit set to sleep e.g. an uplink frame, or a Null frame if there is no uplink data frame to transmit, with the PM bit set to sleep.
  • the PM-bit based mechanism is referred to as LGCY6 in the art.
  • a second power management mechanism uses a PM-Poll frame to solicit downlink frames. Instead of waiting indefinitely for the access point to deliver downlink transmission, the PM-Poll based mechanism utilizes the PM-Poll frame to retrieve the buffered downlink frame from the access point.
  • a mobile station transitions to active mode upon having an uplink data frame to transmit. The mobile station then sends out the uplink transmission. Similar to the PM-bit based mechanism, the access point sets the more data field to indicate the presence of any buffered downlink transmission. If the more data bit is TRUE, the mobile station will continue to send a PM-Poll frame to retrieve the buffered downlink frame.
  • a mobile station can stay in the sleep state since the access point responds to the PM-Poll with an immediate data frame.
  • the PM-Poll based mechanism is referred to as LGCY5 in the art.
  • the PM-bit based mechanism is somewhat inefficient because, for example, the 802.11 standard currently only offers one way for the mobile station to transition to sleep mode, which is by initiating a frame exchange sequence with PM bit set to sleep. As a result, an extra mobile station initiated frame exchange is needed per bi-directional voice transfer in order for the mobile station to signal power state transition. Since the payload of a voice frame is small (e.g. 20 bytes for voice application with 20 ms framing and 8 Kbps vocoder), the overhead incurred by the extra frame exchange could be as high as one third of the traffic between the mobile station and access point.
  • the significant overhead results in the inefficiency on both power consumption and system capacity PM-Poll based mechanism, since a mobile station is not aware of the priority of the buffered downlink frame, the PM-Poll frame is sent as a the best effort access attempt, which is a data traffic mode instead of a voice traffic mode. As a result, the downlink voice transmissions essentially use the best-effort priority instead of the higher voice priority.
  • the system When a system is loaded with both data traffic using best-effort priority with voice traffic, and a mobile station retrieves downlink voice traffic using a power save poll frame transmitted at the same priority as data traffic, the system will be unable to protect the voice traffic from the delays associated with a congested best-effort delivery system.
  • Legacy power save methods may also require an uplink or poll frame to retrieve each buffered frame for the down link, or require immediate response from the access point for a given uplink frame.
  • One method of providing a particular quality of service is to use scheduled service periods at regular intervals for a given mobile station. This scheduled mode of power save deliver is referred to as automatic power save delivery (APSD).
  • the mobile station wakes up at regular intervals and listens to the channel.
  • the access point is synchronized to the service period, and transmits data at the scheduled time.
  • the mobile station can put the WLAN subsystem to sleep during the periods between scheduled service intervals.
  • this method limits the flexibility of the WLAN channel since there is no ability for the mobile station to deviate from the schedule. Therefore, given these shortcomings of the prior art, there is a need for a reliable power management protocol in a WLAN system that permits mobile station with active voice sessions to efficiently enter and exit power save mode without excessive overhead and maintain quality of service in the presence of lower priority traffic.
  • FIG. 1 shows a block system diagram overview of a typical enterprise WLAN system that may support both prior art methods of WLAN transactions as well as those in accordance with the present invention
  • FIG. 2 shows a schematic block diagram of a mobile station for use in a WLAN system, in accordance with the invention
  • FIG. 3 shows a schematic block diagram of an access point for use in a WLAN system, in accordance with the invention
  • FIG. 4 show a flow diagram illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication and using both scheduled and unscheduled transactions, in accordance with the invention
  • FIG. 5 show a flow diagram illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication during an unscheduled transaction, in accordance with the invention
  • FIG. 6 shows a flow chart diagram illustrating a hybrid method of performing power save operation in a mobile station of a WLAN, in accordance with the invention
  • FIG. 7 shows a flow chart diagram of a mobile station frame exchange process during an unscheduled service period, in accordance with the invention.
  • FIG. 8 shows a flow chart diagram of a method of buffering data at an access point, in accordance with the invention.
  • the invention solves the problems associated with the prior art method of scheduled operation by allowing a more flexible use of scheduled and unscheduled transactions.
  • the mobile station first establishes a scheduled stream to be used in association with a high priority access category flow, such as a real time voice call or a video stream, for example. Accordingly, the mobile station enters a low power mode, and waits for a scheduled service period to begin.
  • the scheduled service periods occur at regular intervals and have a predetermined duration. Occasionally the access point may have to terminate the service period before all buffered data can be delivered.
  • the mobile station may receive notice from the access point that the access point still has data buffered for the mobile station, and may indicate the type or access category of data that is buffered at the access point.
  • the mobile station may place its WLAN componentry in a low power mode.
  • the mobile station may then initiate an unscheduled service period before the next scheduled service period to retrieve the remaining data, if conditions allow. For example, before deciding to initiate an unscheduled service period, the mobile station may check its battery status to see if there is sufficient power budget, or it may determine, based on information provided by the access point, that the data remaining at the access point is of an access category that requires immediate attention.
  • the mobile station may also use the unscheduled transaction to service low priority data flows.
  • the mobile station comprises a voice processor 202 for processing voice signals, including transforming signals between digital and analog form.
  • the voice processor is operably coupled to a WLAN subsystem 204 .
  • the WLAN subsystem contains data buffers and radio hardware to send and receive information over a wireless radio frequency link via an antenna 206 .
  • the voice processor converts digital voice and audio data received from the WLAN subsystem to analog form and plays it over a transducer, such as a speaker 208 .
  • the voice processor also receives analog voice and audio signals from a microphone 210 , and converts them to digital signals, which are sent to the WLAN subsystem.
  • the voice processor also performs voice encoding and decoding, by using, for example, vector sum excited linear predictive coding techniques, as is known in the art.
  • voice encoding allows for compression of the voice data.
  • the mobile station may have other media processors, abstracted as box 212 , which may included regular data applications such as email, for example.
  • These other data processors are likewise operably coupled to the WLAN subsystem via bus 214 , for example.
  • As data arrives at the WLAN subsystem it gets buffered in a WLAN buffer 216 and subsequently packetized for transport over IP networks.
  • Each processor sending data to the WLAN subsystem indicates the type of data, and formats the data for transmission, indicating the type of data in the frame. All data processors and the WLAN subsystem are controlled by a controller 218 .
  • the controller dictates the power save operation of the WLAN subsystem, setting it into lower power states when appropriate and powering it up when it is time to transmit or receive data.
  • a WLAN transceiver 302 performs the radio frequency operations necessary for communicating with mobile stations in the vicinity of the access point via an antenna 304 .
  • the access point is connected to networks via gateway network interface 306 , typically via a hard line 316 , such as a coaxial cable, for example.
  • Data received at the access point from mobile stations is immediately forwarded to the gateway for routing to the appropriate network entity.
  • Data received at the access point from the network that is bound for a mobile station may be treated according to one of at least three classifications. First, the mobile station may be in active mode, in which case the data will be buffered only until it can be transmitted.
  • a second category of mobile station power save state is a mobile station in an unreserved or legacy power save mode.
  • a buffer manager 308 buffers the data in an unreserved data buffer 310 upon receiving it from the gateway 306 via a bus 318 .
  • Unreserved data is data that does not belong to a reserved traffic stream.
  • the access point When the particular mobile station for which the unreserved data is buffered transmits to the access point either an unreserved data power save poll frame or a frame that transitions the mobile station to the active state, the access point will respond by transmitting the unreserved data to the polling station from the unreserved data buffer.
  • the manner of delivery may be controlled by the mobile station, where the unreserved data is only delivered in response to a specific polling or trigger frame, or it may be delivered at regularly scheduled and agreed upon time intervals.
  • a third power save classification the access point may receive data for is reserved data bound for a mobile station using the present hybrid power save method. Reserved data is data that belongs to a reserved traffic stream.
  • the buffer manager 308 buffers the data in a reserved buffer, such as reserved buffer 312 .
  • reserved buffer it is meant that the buffer is for buffering data belonging to a reserved traffic stream, such as a real time voice call. Most of the reserved data is intended to be transmitted during scheduled service periods which occur at regular intervals.
  • the unreserved data buffer and reserved buffer may be treated as an aggregate buffer 309 .
  • the access point when the access point is polled by the mobile station during an unscheduled service period the access point empties the aggregate buffer by transmitting all aggregate buffered data to the mobile station.
  • the access point will typically enforce an aging policy so as to prevent too much reserved data from being buffered at the access point.
  • the access point may rely on the mobile station initiating unscheduled transaction to retrieve remaining reserved data rather than discarding reserved data as in other methods.
  • the controller 314 Supervising the operation of the buffer manager 308 , gateway 306 , and transceiver 302 is a controller 314 .
  • the controller also administers resource management and controls resources so that quality of service may be assured as needed for reserved traffic streams.
  • the controller is operably coupled to a memory 315 , which it uses to track the status of call, mobile station power save states, and other parameters.
  • FIG. 4 there is shown a flow diagram 400 illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication and using both scheduled and unscheduled transactions in accordance with the invention.
  • the mobile station and access point engage in scheduled transactions at regular intervals 402 .
  • Prior to the beginning of a scheduled service period the mobile station exits low power mode by powering up the WLAN subsystem.
  • the schedule is predetermined and agreed upon by the access point and mobile station.
  • the access point will typically begin transmitting data to the mobile station, if there is data to transmit, under the assumption that the mobile station is awake and receiving the data.
  • the access point may be finishing a transaction with another mobile station at the beginning of the scheduled service period, so the mobile station simply waits for its data to appear in WLAN channel.
  • the access point transmits a frame indicating whether the access point still has data buffered at the access point for the mobile station that could not be delivered within the duration of the scheduled service period.
  • Such indication is easily given in a control field of the packet header of the frame.
  • the control field may include a bitmap describing the access categories and whether data for each of the access categories is present. Thus, the control field allows the mobile station to determine the priority of the data remaining at the access point.
  • the mobile station may initiate an unscheduled service period 404 if conditions allow.
  • the unscheduled transaction can then be used to retrieve the remaining data, as well as transmit data to the access point for routing.
  • the access point may limit the number of unscheduled service periods a mobile station can initiate between scheduled service periods.
  • FIG. 5 there is shown a flow diagram 500 illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system during an unscheduled service period initiated by the mobile station between scheduled service periods.
  • the traffic flow typically includes reserved data, meaning that the mobile station and access point have negotiated a priority and medium time for the reserved traffic stream to ensure a desired quality of communication, where the medium time indicates the amount of time per negotiated service interval the access point will apportion to the traffic stream or access category.
  • voice traffic since it occurs in real time, it is desirable to establish a reserved traffic stream for the communication.
  • the system carrying out the flow shown here in FIGS. 4–5 may be performed by a system using configurations and system components similar to those shown in FIGS. 1–3 with control software designed in accordance with the teachings herein.
  • the mobile station transmissions appear on the bottom flow line 502 , while the access point transmissions appear on the top flow line 504 .
  • the mobile station and access point will have established a reserved traffic stream, meaning the access point has reserved certain resources to maintain voice quality of the traffic stream. That is, the access point will usually be able to service the flow in a timely manner so that the real time effect of the flow is maintained.
  • admission control should be required for certain services, such as real time voice and video streaming.
  • a mobile station e.g.
  • the access point should acknowledge the admission of the flow to the mobile station.
  • admitting the flow it is meant that the data flow will be a reserved traffic stream having a unique traffic stream identifier.
  • the reserved traffic stream will have a priority classification and will be apportioned a minimum amount of channel access time.
  • the scheduled power save mechanism can be established by mobile station implicitly by the use of a traffic specification reservation. In frames containing data for the reserved traffic stream, the unique traffic stream identifier (TSID) will be included.
  • the mobile station can choose no power save operation, legacy power save operation, scheduled power save operation only, or the present hybrid power save operation. After the traffic flow is admitted by the access point, the mobile station puts the WLAN subsystem in a low power state.
  • the mobile station After the WLAN subsystem is placed in low power mode, the mobile station maintains a service interval timer to maintain real time operation of the flow during scheduled service periods. However, if data remains at the access point after a scheduled service period, the mobile station may choose to initiate an unscheduled service period. At the beginning of an unscheduled service period, the mobile station activates the WLAN subsystem at time 506 . After which, during the time period 507 , the mobile station begins contending for the WLAN channel. The mobile station initiates the unscheduled transaction by transmitting a polling frame 508 .
  • the polling frame may be a voice frame, which in the preferred embodiment contains a unique traffic stream identifier, and a frame of voice data if the user of the mobile station is presently speaking, or if there is no voice data to transmit presently, the polling frame will be a null frame.
  • the polling frame will identify the reserved traffic stream.
  • the polling frame may also include signaling to indicate a desire for the access point to use an aggregate response method so that both reserved and unreserved data may be received from the access point. Alternatively, the aggregate response may be the default response mode.
  • the access point after the access point receives the polling frame, it transmits an acknowledgement 510 within a short interframe space time period 512 , which is a scheduled event, in accordance with the IEEE 802.11 specification.
  • the access point transmits at least one response frame 516 to the mobile station, assuming the access point has aggregate buffered data for the mobile station. Assuming there is both unreserved data and reserved data in the aggregate buffer, at least a second response frame 518 will be transmitted. The access point will continue to transmit response frames until the aggregate buffer is empty, or, alternatively, if the access point must perform other scheduled tasks.
  • Each response frame includes an end of uplink service period (EUSP) bit, such as a MORE — DATA bit to indicate whether there is more data coming from the access point, or whether the present response frame is the last response frame for the service period.
  • EUSP uplink service period
  • the access point may not completely empty the aggregate buffer of unreserved data if the access point is presently servicing a high number of reserved traffic streams for other mobile station, and the delivering the unreserved data may interfere with the delivery of reserved traffic.
  • the time period between receiving the polling frame and transmitting the response frame can vary as the access point may have to finish attending to another flow for another mobile station. In the preferred embodiment, there will typically be a turnaround interframe space time period 514 between the acknowledgement and the response frame. As soon as possible, the access point will acquire the WLAN channel and transmit the response frame or frames. However, the response frame is not sent with regard to any predetermined schedule. That is, mobile station maintains the WLAN subsystem powered up for an indeterminate period of time. Of course, a reasonable maximum period of time could be observed to prevent the mobile station waiting too long for a response frame or remaining active too long.
  • the mobile station can take appropriate action, such as polling the access point a second time during the service period to check the status of the power save buffers and retrieve any frames waiting to be transmitted.
  • the response frame will identify the reserved traffic stream when it contains reserved data. If the access point has data in the reserved buffer associated with the reserved traffic stream, the access point will transmit a frame of data from the buffer. If there is no data in the aggregate buffer, the access point will transmit a null frame. Alternatively, if the aggregate buffer is empty, then the acknowledgement 510 may indicate such. In the response frame there will be signaling information, such as an EUSP bit designated to indicate the end of the present service period, which may occur because there is no more data to transmit or because the access point must perform other scheduled tasks.
  • signaling information such as an EUSP bit designated to indicate the end of the present service period, which may occur because there is no more data to transmit or because the access point must perform other scheduled tasks.
  • a MORE — DATA bit may be used as the EUSP bit. If the MORE — DATA bit is cleared in the response frame, it indicates the end of the unscheduled service period due to successful transmission of all buffered frame for the mobile station in the aggregate buffer, or the end of the unscheduled service period due to time considerations. If the access point transmits a null frame in the response frame, access point may also use the MORE — DATA bit to indicate there is no more data and to signal that the present unscheduled service period is over.
  • the mobile station transmits an acknowledgement 520 within a short interframe space time period 518 . If the response frame indicated the end of the present unscheduled service period, the mobile station then places the WLAN subsystem into a low power state after receiving the response frame at time 522 .
  • FIG. 6 there is shown a flow chart diagram 600 illustrating a hybrid method of performing power save operation in a mobile station of a WLAN in accordance with the invention.
  • the mobile station and access point have negotiated a reserved traffic stream and established a schedule by which to exchange data for the reserved traffic stream and the mobile station has put its WLAN subsystem in low power mode until the beginning of a scheduled service period.
  • the mobile station commences powering up the WLAN subsystem ( 604 ) to begin the scheduled transaction ( 606 ).
  • the access point transmits reserved data to the mobile station, and identified the traffic stream with the unique traffic stream identifier.
  • the access point still may have data left to transmit to the mobile station, and indicates such in a last frame transmitted to the mobile station.
  • the access point may indicate detailed, per access category buffering information describing the access categories of information buffered at the access point. In IEEE 802.11 there are presently four access categories described, including voice, video, and best effort categories.
  • the mobile station may transmit data to the access point as well.
  • the mobile station may place the WLAN subsystem back into a low power state ( 608 ).
  • the mobile station determines whether an unscheduled transaction is appropriate ( 610 ), such as by the detailed access category buffering information provided by the access point, for example.
  • the mobile station may weigh various parameters, such as the present battery status of the mobile station, the type of data present at the access point, and so on. If the mobile station decides an unscheduled transaction is appropriate, the mobile station brings the WLAN subsystem out of low power mode to active mode ( 612 ), and initiates an unscheduled transaction ( 614 ) in accordance with the method shown and described in FIGS. 4–5 . Once the unscheduled transaction is over, the mobile station again places the WLAN subsystem in low power mode ( 616 ). The mobile station the waits for the next scheduled service period ( 618 ) and repeats the process.
  • the mobile station decides an unscheduled transaction is appropriate, the mobile station brings the WLAN subsystem out of low power mode to active mode ( 612 ), and initiates an unscheduled transaction ( 614 ) in accordance with the method shown and described in FIGS. 4–5 . Once the unscheduled transaction is over, the mobile station again places the WLAN subsystem in low power mode ( 616 ). The mobile station the wait
  • the mobile station had determined that an unscheduled transaction would not be appropriate ( 610 ), due to, for example, low battery power or the data at the access point is of low priority, the mobile station will skip the unscheduled transaction and wait for the next scheduled transaction ( 618 ).
  • FIG. 7 there is shown a flow chart diagram of a mobile station frame exchange process during an unscheduled transaction, in accordance with the invention.
  • the mobile station checks to see if there is data presently pending for the reserved traffic stream from the voice or other real time media processors. If not, then the mobile station waits as the polling window timer times a polling window. The mobile station also contends for the WLAN channel during this time. Once the channel is acquired, the mobile station transmits a polling frame ( 702 ).
  • the polling frame will contain data if data was pending, otherwise the polling frame will be a null frame.
  • the polling frame identifies the reserved traffic stream.
  • the reserved traffic stream is preferably identified by its TSID, and the presence of the traffic stream identifier indicates to the access point that the mobile station is using an unscheduled transaction.
  • aggregate response from the access point is the default mode, but the aggregate response mode may also be selectable, and the desire to receive an aggregate response may be indicated in the polling frame.
  • the access point transmits and acknowledgment which is received by the mobile station ( 703 ). If the acknowledgement is not received ( 704 ), the mobile station may back off by waiting, then retransmit the polling frame. After transmitting the polling frame, and, in the preferred mode, receiving the acknowledgment, the mobile station then waits for the access point to respond. Since the response is not scheduled, the time of the wait is variable, although the mobile station may have a preselected maximum time period to wait before undertaking an error procedure, assuming a failure of access point to respond. However, assuming normal operation, the access point will transmit an aggregation of response frames which will be received by the mobile station ( 706 ).
  • data belonging to the traffic stream identified by the TSID used by the mobile station in the polling frame may be transmitted first, before unreserved data, in the aggregate response. Again, in the preferred mode, the mobile station will transmit an acknowledgement to assure the access point of a successful delivery.
  • the mobile station Upon receiving the response frame, the mobile station checks the EUSP bit to see if the UPSD service period is over. In the preferred embodiment, the MORE — DATA bit may be used to signal when more date is coming from the access point ( 708 ), and when it is set it indicates that the service period is continuing until at least one more response frame is received. If the MORE — DATA bit indicates subsequent frames are coming, then the mobile station remains active to receive them as it did for the first response frame.
  • subsequent response frames may contain data for a different reserved traffic stream also in use by the mobile station, or for the present reserved traffic stream.
  • FIG. 8 there is shown a flow chart diagram 800 of a method of buffering data at an access point, in accordance with the invention.
  • the access point At the start ( 802 ) of the method, the access point has admitted a reserved traffic stream for establishing a call to a mobile station. Data packets arrive from a network at the access point that are designated for the mobile station. As data packets arrive, the access point checks to see if the data packet is destined for a mobile station that is presently in a power save mode ( 804 ). If the mobile station for which an arriving packet is destined is not presently in a power save mode, the access point transmits the packet ( 806 ) to the mobile station.
  • the access point must determine whether the mobile station is using a legacy power save mode or the present unscheduled power save delivery mode ( 808 ). If the mobile station is using a legacy power save mode, then the access point buffers the packet in a unreserved buffer ( 810 ) and will signal the mobile station as to the state of its buffer in, for example, a periodic beacon frame transmitted by the access point. If the packet is associated with an admitted flow for a mobile station using power save mode, then the packet is stored in the reserved buffer ( 812 ).
  • the invention provides A method of performing power save operation in a wireless local area network (WLAN) by a mobile station in which a recurring service period schedule set up between the mobile station and an access point.
  • the scheduled service periods occur at periodic intervals and are for maintaining a reserved traffic stream.
  • the reserved traffic stream is identified by a reserved traffic stream identifier, and the mobile station has its WLAN subsystem initially in a low power mode.
  • the method commences by powering up the WLAN subsystem of the mobile station and commencing a scheduled service period.
  • the mobile stations receives from the access point an indication that the access point has more data in a buffer of the access point for the mobile station.
  • the mobile station After receiving the last frame of the scheduled service period, the mobile station places the WLAN subsystem into low power mode.
  • the mobile station then commences initiating an unscheduled service period to retrieve the remaining data buffered at the access point for the mobile station.
  • the unscheduled service period begins by powering up the WLAN subsystem and transmitting a polling frame to the access point.
  • the polling frame includes the reserved traffic stream identifier.
  • the mobile station receives at least one response frame from the access point.
  • the mobile station places the WLAN subsystem into low power mode.
  • receiving the response frame includes receiving an aggregate response in which both reserved and unreserved data is received.
  • the aggregate mode may be a default mode, or it may be triggered by transmitting the polling frame with an aggregation bit set.
  • the present method also prescribes a method of retrieving data from an access point by a mobile station in a wireless local area network (WLAN), where the reserved data corresponds to a reserved traffic stream and is identified by a reserved traffic stream identifier.
  • the method includes performing a scheduled transaction between the mobile station and access point during a scheduled service period.
  • the mobile station transitions from a low power WLAN mode to an active WLAN mode to commence the scheduled transaction, and then transitions from the active WLAN mode to a low power WLAN mode upon completion the scheduled transaction.
  • After the scheduled transaction is complete.
  • the mobile station commences performing an unscheduled transaction between the mobile station and access point during an unscheduled service period.
  • the mobile station transitions from a low power WLAN mode to an active WLAN mode to initiate the unscheduled transaction, and then transitions from the active WLAN mode to a low power WLAN mode upon completing the unscheduled transaction.
  • the unscheduled transaction may be performed in response to the access point indicating at the end of the scheduled service period that the access point still has data for the mobile station, or, alternatively, the mobile station may have data to transmit to the access point. If the access point indicates at the end of the scheduled transaction that there is still data buffered at the access point, the access point may indicate the type of data, such as the access category of the data and whether the data is part of a reserved traffic stream. Data that is part of a reserved traffic stream may be part of a live voice call.
  • the mobile station may decide whether or not to initiate an unscheduled service period by checking various parameters, such as, for example, battery power status, signal quality level, the priority of the data buffered at the access point, and so on.

Abstract

A mobile station establishes a schedule by which data is exchanged with an access point. The schedule allows the mobile station to use a low power mode at times outside of the scheduled service periods. However, the mobile station may occasionally need to retrieve additional data from the access point, or transmit additional data to the access point, and so initiates an unscheduled service period to do so.

Description

TECHNICAL FIELD
This invention relates in general to wireless local area networks, and more particularly to power save methods for reducing power consumption at a mobile station while engaged in a time sensitive communication activity.
BACKGROUND OF THE INVENTION
Wireless LAN (WLAN) systems providing broadband wireless access have experienced a spectacular rise in popularity in recent years. While the principal application of these systems has been in providing network connectivity to portable and mobile devices running data applications such as, for example, email and web browsing, there has been a tremendous and growing interest in supporting isochronous services such as telephony service and streaming video.
One of the key issues facing wireless system designers when considering voice and other time-sensitive services over a WLAN connection, such as one described by the IEEE 802.11 specification, is the power consumption of handheld devices. For example, in order to deliver competitive talk time and standby time, as compared to digital cordless or cellular devices, power conservation during voice calls become necessary. Several organizations have proposed power-efficient operation via transmit power control and physical layer rate adaptation for systems that rely on a centrally controlled contention-free channel access scheme. However, such approaches can be complex to implement and may not provide the power savings required to justify the complexity.
The 802.11 standard defines procedures which can be used to implement power management in a handheld device during periods of inactivity. In particular, three distinct building blocks are provided to support power savings: a Wakeup Procedure, a Sleep Procedure, and a Power-save Poll (PS-Poll) Procedure. A mobile client voice station (mobile station) can combine these building blocks in various manners to support power management for different applications.
Wakeup Procedure: There are generally two reasons for the mobile station to wake up, namely to transmit pending data or to retrieve buffered data from the fixed station serving the mobile station, known as an access point. Waking up to transmit data is a straightforward operation, driven by the mobile station. The decision to wake up and receive data is also made by the mobile station after monitoring its pending data bit in a periodic beacon frame transmitted by its access point. Once the mobile station decides to transition from sleep mode to active mode, it notifies the access point by sending an uplink frame with the power-save (PS) bit set to active. Following such transmission, the mobile station remains active so the access point can send any buffered downlink frames afterward.
Sleep Procedure: Similar to the wakeup procedure, a mobile station in the active mode needs to complete a successful mobile station-initiated frame exchange sequence with PS bit set to sleep to transition into the sleep mode. Following this frame exchange sequence, the access point buffers all the downlink frames to this mobile station.
PS-Poll Procedure: Instead of waiting for the access point to transmit the buffered downlink frames, a power-save mobile station can solicit an immediate delivery from its access point by using a PS-Poll frame. Upon receiving this PS-Poll, the access point can immediately send one buffered downlink frame (immediate data response) or simply send an acknowledgement message and response with a data frame later (delayed data response). For the immediate data response case, a mobile station can stay in sleep state after finishing this frame exchange since there is no need for the mobile station to transition to active state given that the access point can only send a buffered downlink frame after receiving a PS-poll from the mobile station. On the other hand, for the delayed data response case, the mobile station has to transition to the active state until receiving a downlink frame from the access point.
The architecture of a simple enterprise WLAN system is depicted in FIG. 1. Referring now to FIG. 1, there is shown a block system diagram overview 100 of a typical enterprise WLAN system. It includes an infrastructure access network 101, consisting of an Access Point 102 and mobile stations such as a data stations 104 and a voice station 106. The mobile stations are connected to the access point via a WLAN radio link 108. The access point is wired to a distribution network, including voice and data gateways 110, 112 respectively, through a switch 114. The voice station runs a Voice-over-IP (VoIP) application, which establishes a peer-to-peer connection with the voice gateway, representing the other end of the voice call, and which routes voice data to a voice network 116. Data stations may connect to the data gateway via the access network and connect to, for example, a wide area network 118. The impact of data traffic on voice quality should be considered. It is assumed that both the voice and data stations employ a prioritized contention-based quality of service mechanism.
VoIP traffic characteristics make voice over WLAN applications uniquely suited for power save operation. In particular, VoIP applications periodically generate voice frames, where the inter-arrival time between frames depends upon the voice coder chosen for an application. The process of encapsulating voice frames into IP packets is commonly referred to as packetization, which is often assumed to occur once every 20 millisecond. A typical VoIP conversation involves a bi-directional constant bit rate flow of VoIP frames, including an uplink flow from the handset to a voice gateway and a downlink flow in the reverse direction.
Since the station generally knows in advance the frame arrival rate, delay, and bandwidth requirements of its voice application, it can reserve resources and set up power management for its voice flows in agreement with the access point. A mobile station may forgo power save mode, and remain in active mode, always ready for the downlink voice transmission. In this case, the access point may transmit downlink voice frames as they arrive. However, if power save is desired, the mobile station may employ the power save building blocks described previously to wake up, exchange the VoIP frame with its access point, and go back to sleep.
In a shared-medium network, such as the access network shown in FIG. 1, it is important to prioritize VoIP traffic over traffic requiring only best-effort delivery, such as the traffic generated by application that can adapt to the amount of bandwidth available in the network and do not request or require a minimum throughput or delay. Prioritization allows the system to minimize the delay experienced by delay-sensitive traffic. A contention-based channel access scheme offering prioritized access named Enhanced Distributed Channel Access (EDCA) has been specified in the IEEE 802.11e draft, and is suitable for VoIP applications. It is based upon the Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) mechanism defined in 802.11. Stations with voice frames to send must first sense the channel for activity, before transmitting. If the channel has been idle for at least a specified period of time, called an arbitration inter-frame space (AIFS), the mobile station can immediately begin its transmission. Otherwise, the mobile station backs off and waits for the channel to be idle for a random amount of time, which is equal to an AIFS period plus a uniformly distributed value between zero and a contention window (CW) time period value. The CW is further bounded by Minimum contention window (CWmin) and Maximum contention window (CWmax). EDCA provides prioritized access control by adjusting contention parameters: AIFS, CWmin, and CWmax. By selecting different values of AIFS, CWmin, and CWmax for different access categories, the priority to access the medium can be regulated and differentiated. In general, small AIFS, CWmin, and CWmax values result in higher access priority.
It is possible for a mobile station to use information such as the inter-arrival time of downlink voice frames, along with a power-save mechanism, to put itself to sleep between two consecutive voice frames. Presently there are power save procedures described in various papers and WLAN related specifications.
The first prior art power management mechanism utilizes a bit in the packet header. The bit is designated as a power management (PM) bit to signal the change of the power state of the mobile station to the access point. First, a mobile station transitions from sleep mode to active mode upon having an uplink data frame to transmit by setting the PM bit to active in an uplink voice frame to notify the change of its power state. Knowing that there will be one corresponding downlink frame buffered at the access point, because uplink and downlink vocoder share the same voice frame duration, the mobile station stays in active mode for the downlink transmission. After receiving the uplink transmission, the access point then sends buffered downlink frames to the mobile station. In the last downlink frame, the access point sets the “more data” bit to FALSE to communicate the end of the downlink transmission. Finally, the mobile station needs to complete a successful station-initiated frame exchange sequence with PM bit set to sleep to transition into the sleep mode. (e.g. an uplink frame, or a Null frame if there is no uplink data frame to transmit, with the PM bit set to sleep). In the following context, the PM-bit based mechanism is referred to as LGCY6 in the art.
A second power management mechanism uses a PM-Poll frame to solicit downlink frames. Instead of waiting indefinitely for the access point to deliver downlink transmission, the PM-Poll based mechanism utilizes the PM-Poll frame to retrieve the buffered downlink frame from the access point. First, a mobile station transitions to active mode upon having an uplink data frame to transmit. The mobile station then sends out the uplink transmission. Similar to the PM-bit based mechanism, the access point sets the more data field to indicate the presence of any buffered downlink transmission. If the more data bit is TRUE, the mobile station will continue to send a PM-Poll frame to retrieve the buffered downlink frame. Unlike the PM-bit based mechanism, a mobile station can stay in the sleep state since the access point responds to the PM-Poll with an immediate data frame. In the following context, the PM-Poll based mechanism is referred to as LGCY5 in the art.
There are a couple of issues in supporting power-efficient VoIP operation using the current WLAN power save mechanisms. First, the PM-bit based mechanism is somewhat inefficient because, for example, the 802.11 standard currently only offers one way for the mobile station to transition to sleep mode, which is by initiating a frame exchange sequence with PM bit set to sleep. As a result, an extra mobile station initiated frame exchange is needed per bi-directional voice transfer in order for the mobile station to signal power state transition. Since the payload of a voice frame is small (e.g. 20 bytes for voice application with 20 ms framing and 8 Kbps vocoder), the overhead incurred by the extra frame exchange could be as high as one third of the traffic between the mobile station and access point. The significant overhead results in the inefficiency on both power consumption and system capacity PM-Poll based mechanism, since a mobile station is not aware of the priority of the buffered downlink frame, the PM-Poll frame is sent as a the best effort access attempt, which is a data traffic mode instead of a voice traffic mode. As a result, the downlink voice transmissions essentially use the best-effort priority instead of the higher voice priority. When a system is loaded with both data traffic using best-effort priority with voice traffic, and a mobile station retrieves downlink voice traffic using a power save poll frame transmitted at the same priority as data traffic, the system will be unable to protect the voice traffic from the delays associated with a congested best-effort delivery system. Legacy power save methods may also require an uplink or poll frame to retrieve each buffered frame for the down link, or require immediate response from the access point for a given uplink frame. One method of providing a particular quality of service is to use scheduled service periods at regular intervals for a given mobile station. This scheduled mode of power save deliver is referred to as automatic power save delivery (APSD). The mobile station wakes up at regular intervals and listens to the channel. The access point is synchronized to the service period, and transmits data at the scheduled time. Thus, the mobile station can put the WLAN subsystem to sleep during the periods between scheduled service intervals. However, this method limits the flexibility of the WLAN channel since there is no ability for the mobile station to deviate from the schedule. Therefore, given these shortcomings of the prior art, there is a need for a reliable power management protocol in a WLAN system that permits mobile station with active voice sessions to efficiently enter and exit power save mode without excessive overhead and maintain quality of service in the presence of lower priority traffic.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block system diagram overview of a typical enterprise WLAN system that may support both prior art methods of WLAN transactions as well as those in accordance with the present invention;
FIG. 2 shows a schematic block diagram of a mobile station for use in a WLAN system, in accordance with the invention;
FIG. 3 shows a schematic block diagram of an access point for use in a WLAN system, in accordance with the invention;
FIG. 4 show a flow diagram illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication and using both scheduled and unscheduled transactions, in accordance with the invention;
FIG. 5 show a flow diagram illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication during an unscheduled transaction, in accordance with the invention;
FIG. 6 shows a flow chart diagram illustrating a hybrid method of performing power save operation in a mobile station of a WLAN, in accordance with the invention;
FIG. 7 shows a flow chart diagram of a mobile station frame exchange process during an unscheduled service period, in accordance with the invention; and
FIG. 8 shows a flow chart diagram of a method of buffering data at an access point, in accordance with the invention; and
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
The invention solves the problems associated with the prior art method of scheduled operation by allowing a more flexible use of scheduled and unscheduled transactions. The mobile station first establishes a scheduled stream to be used in association with a high priority access category flow, such as a real time voice call or a video stream, for example. Accordingly, the mobile station enters a low power mode, and waits for a scheduled service period to begin. The scheduled service periods occur at regular intervals and have a predetermined duration. Occasionally the access point may have to terminate the service period before all buffered data can be delivered. At the end of the scheduled service period, the mobile station may receive notice from the access point that the access point still has data buffered for the mobile station, and may indicate the type or access category of data that is buffered at the access point. At the end of the scheduled service period, the mobile station may place its WLAN componentry in a low power mode. The mobile station may then initiate an unscheduled service period before the next scheduled service period to retrieve the remaining data, if conditions allow. For example, before deciding to initiate an unscheduled service period, the mobile station may check its battery status to see if there is sufficient power budget, or it may determine, based on information provided by the access point, that the data remaining at the access point is of an access category that requires immediate attention. The mobile station may also use the unscheduled transaction to service low priority data flows.
Referring now to FIG. 2, there is shown a schematic block diagram 200 of a mobile station for use in a WLAN system, in accordance with the invention. The mobile station comprises a voice processor 202 for processing voice signals, including transforming signals between digital and analog form. The voice processor is operably coupled to a WLAN subsystem 204. The WLAN subsystem contains data buffers and radio hardware to send and receive information over a wireless radio frequency link via an antenna 206. The voice processor converts digital voice and audio data received from the WLAN subsystem to analog form and plays it over a transducer, such as a speaker 208. The voice processor also receives analog voice and audio signals from a microphone 210, and converts them to digital signals, which are sent to the WLAN subsystem. Preferably the voice processor also performs voice encoding and decoding, by using, for example, vector sum excited linear predictive coding techniques, as is known in the art. The use of voice encoding allows for compression of the voice data. In addition to voice processing, the mobile station may have other media processors, abstracted as box 212, which may included regular data applications such as email, for example. These other data processors are likewise operably coupled to the WLAN subsystem via bus 214, for example. As data arrives at the WLAN subsystem, it gets buffered in a WLAN buffer 216 and subsequently packetized for transport over IP networks. Each processor sending data to the WLAN subsystem indicates the type of data, and formats the data for transmission, indicating the type of data in the frame. All data processors and the WLAN subsystem are controlled by a controller 218. The controller dictates the power save operation of the WLAN subsystem, setting it into lower power states when appropriate and powering it up when it is time to transmit or receive data.
Referring now to FIG. 3, there is shown a schematic block diagram 300 of an access point for use in a WLAN system, in accordance with the invention. A WLAN transceiver 302 performs the radio frequency operations necessary for communicating with mobile stations in the vicinity of the access point via an antenna 304. The access point is connected to networks via gateway network interface 306, typically via a hard line 316, such as a coaxial cable, for example. Data received at the access point from mobile stations is immediately forwarded to the gateway for routing to the appropriate network entity. Data received at the access point from the network that is bound for a mobile station may be treated according to one of at least three classifications. First, the mobile station may be in active mode, in which case the data will be buffered only until it can be transmitted. In such a case the intent is to not delay transmission to the mobile station any longer than necessary, and data for a mobile station of this classification is transmitted typically transmitted using a priority-based queuing discipline. A second category of mobile station power save state is a mobile station in an unreserved or legacy power save mode. For this second classification, a buffer manager 308 buffers the data in an unreserved data buffer 310 upon receiving it from the gateway 306 via a bus 318. Unreserved data is data that does not belong to a reserved traffic stream. When the particular mobile station for which the unreserved data is buffered transmits to the access point either an unreserved data power save poll frame or a frame that transitions the mobile station to the active state, the access point will respond by transmitting the unreserved data to the polling station from the unreserved data buffer. The manner of delivery may be controlled by the mobile station, where the unreserved data is only delivered in response to a specific polling or trigger frame, or it may be delivered at regularly scheduled and agreed upon time intervals. A third power save classification the access point may receive data for is reserved data bound for a mobile station using the present hybrid power save method. Reserved data is data that belongs to a reserved traffic stream. For a reserved flow data, the buffer manager 308 buffers the data in a reserved buffer, such as reserved buffer 312. By reserved buffer it is meant that the buffer is for buffering data belonging to a reserved traffic stream, such as a real time voice call. Most of the reserved data is intended to be transmitted during scheduled service periods which occur at regular intervals.
Although illustrated here as two separate physical buffers, one skilled in the art will understand that a variety of buffering techniques may be used to keep reserved and unreserved data separate, without necessarily requiring separate physical buffers. Furthermore, given that the access point will respond to the polling frame with an aggregate response, the unreserved data buffer and reserved buffer may be treated as an aggregate buffer 309. In one embodiment of the invention when the access point is polled by the mobile station during an unscheduled service period the access point empties the aggregate buffer by transmitting all aggregate buffered data to the mobile station. In other power save methods, the access point will typically enforce an aging policy so as to prevent too much reserved data from being buffered at the access point. However, using the present hybrid method, the access point may rely on the mobile station initiating unscheduled transaction to retrieve remaining reserved data rather than discarding reserved data as in other methods.
Supervising the operation of the buffer manager 308, gateway 306, and transceiver 302 is a controller 314. The controller also administers resource management and controls resources so that quality of service may be assured as needed for reserved traffic streams. The controller is operably coupled to a memory 315, which it uses to track the status of call, mobile station power save states, and other parameters.
Referring now to FIG. 4, there is shown a flow diagram 400 illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system for supporting voice quality communication and using both scheduled and unscheduled transactions in accordance with the invention. The mobile station and access point engage in scheduled transactions at regular intervals 402. Prior to the beginning of a scheduled service period the mobile station exits low power mode by powering up the WLAN subsystem. The schedule is predetermined and agreed upon by the access point and mobile station. The access point will typically begin transmitting data to the mobile station, if there is data to transmit, under the assumption that the mobile station is awake and receiving the data. It is contemplated that the access point may be finishing a transaction with another mobile station at the beginning of the scheduled service period, so the mobile station simply waits for its data to appear in WLAN channel. At the end of the scheduled service period, the access point transmits a frame indicating whether the access point still has data buffered at the access point for the mobile station that could not be delivered within the duration of the scheduled service period. Such indication is easily given in a control field of the packet header of the frame. The control field may include a bitmap describing the access categories and whether data for each of the access categories is present. Thus, the control field allows the mobile station to determine the priority of the data remaining at the access point. In response to the presence of data remaining at the access point, the mobile station may initiate an unscheduled service period 404 if conditions allow. The unscheduled transaction can then be used to retrieve the remaining data, as well as transmit data to the access point for routing. The access point may limit the number of unscheduled service periods a mobile station can initiate between scheduled service periods.
Referring now to FIG. 5, there is shown a flow diagram 500 illustrating an overview of the traffic flow between a mobile station and an access point in a WLAN system during an unscheduled service period initiated by the mobile station between scheduled service periods. The traffic flow typically includes reserved data, meaning that the mobile station and access point have negotiated a priority and medium time for the reserved traffic stream to ensure a desired quality of communication, where the medium time indicates the amount of time per negotiated service interval the access point will apportion to the traffic stream or access category. With voice traffic, since it occurs in real time, it is desirable to establish a reserved traffic stream for the communication. The system carrying out the flow shown here in FIGS. 4–5 may be performed by a system using configurations and system components similar to those shown in FIGS. 1–3 with control software designed in accordance with the teachings herein.
The mobile station transmissions appear on the bottom flow line 502, while the access point transmissions appear on the top flow line 504. As mentioned, prior to the transaction illustrated here, the mobile station and access point will have established a reserved traffic stream, meaning the access point has reserved certain resources to maintain voice quality of the traffic stream. That is, the access point will usually be able to service the flow in a timely manner so that the real time effect of the flow is maintained. To prevent an overloaded scenario in a WLAN voice system, where an excessive number of high priority users might make it difficult for a system to satisfy quality of service requirements, admission control should be required for certain services, such as real time voice and video streaming. For example, in an infrastructure based voice WLAN system, a mobile station (e.g. voice user) should set up a bi-directional traffic flow for voice using a known traffic specification, and the access point should acknowledge the admission of the flow to the mobile station. By admitting the flow, it is meant that the data flow will be a reserved traffic stream having a unique traffic stream identifier. The reserved traffic stream will have a priority classification and will be apportioned a minimum amount of channel access time. During the connection setup period, the scheduled power save mechanism can be established by mobile station implicitly by the use of a traffic specification reservation. In frames containing data for the reserved traffic stream, the unique traffic stream identifier (TSID) will be included. The mobile station can choose no power save operation, legacy power save operation, scheduled power save operation only, or the present hybrid power save operation. After the traffic flow is admitted by the access point, the mobile station puts the WLAN subsystem in a low power state.
After the WLAN subsystem is placed in low power mode, the mobile station maintains a service interval timer to maintain real time operation of the flow during scheduled service periods. However, if data remains at the access point after a scheduled service period, the mobile station may choose to initiate an unscheduled service period. At the beginning of an unscheduled service period, the mobile station activates the WLAN subsystem at time 506. After which, during the time period 507, the mobile station begins contending for the WLAN channel. The mobile station initiates the unscheduled transaction by transmitting a polling frame 508. The polling frame may be a voice frame, which in the preferred embodiment contains a unique traffic stream identifier, and a frame of voice data if the user of the mobile station is presently speaking, or if there is no voice data to transmit presently, the polling frame will be a null frame. The polling frame will identify the reserved traffic stream. The polling frame may also include signaling to indicate a desire for the access point to use an aggregate response method so that both reserved and unreserved data may be received from the access point. Alternatively, the aggregate response may be the default response mode.
In the preferred embodiment, after the access point receives the polling frame, it transmits an acknowledgement 510 within a short interframe space time period 512, which is a scheduled event, in accordance with the IEEE 802.11 specification. In response to receiving the polling frame, the access point transmits at least one response frame 516 to the mobile station, assuming the access point has aggregate buffered data for the mobile station. Assuming there is both unreserved data and reserved data in the aggregate buffer, at least a second response frame 518 will be transmitted. The access point will continue to transmit response frames until the aggregate buffer is empty, or, alternatively, if the access point must perform other scheduled tasks. Each response frame includes an end of uplink service period (EUSP) bit, such as a MOREDATA bit to indicate whether there is more data coming from the access point, or whether the present response frame is the last response frame for the service period. It is contemplated that the access point may not completely empty the aggregate buffer of unreserved data if the access point is presently servicing a high number of reserved traffic streams for other mobile station, and the delivering the unreserved data may interfere with the delivery of reserved traffic.
The time period between receiving the polling frame and transmitting the response frame can vary as the access point may have to finish attending to another flow for another mobile station. In the preferred embodiment, there will typically be a turnaround interframe space time period 514 between the acknowledgement and the response frame. As soon as possible, the access point will acquire the WLAN channel and transmit the response frame or frames. However, the response frame is not sent with regard to any predetermined schedule. That is, mobile station maintains the WLAN subsystem powered up for an indeterminate period of time. Of course, a reasonable maximum period of time could be observed to prevent the mobile station waiting too long for a response frame or remaining active too long. In the event the maximum period occurs, the mobile station can take appropriate action, such as polling the access point a second time during the service period to check the status of the power save buffers and retrieve any frames waiting to be transmitted. The response frame will identify the reserved traffic stream when it contains reserved data. If the access point has data in the reserved buffer associated with the reserved traffic stream, the access point will transmit a frame of data from the buffer. If there is no data in the aggregate buffer, the access point will transmit a null frame. Alternatively, if the aggregate buffer is empty, then the acknowledgement 510 may indicate such. In the response frame there will be signaling information, such as an EUSP bit designated to indicate the end of the present service period, which may occur because there is no more data to transmit or because the access point must perform other scheduled tasks. In the preferred embodiment a MOREDATA bit may be used as the EUSP bit. If the MOREDATA bit is cleared in the response frame, it indicates the end of the unscheduled service period due to successful transmission of all buffered frame for the mobile station in the aggregate buffer, or the end of the unscheduled service period due to time considerations. If the access point transmits a null frame in the response frame, access point may also use the MOREDATA bit to indicate there is no more data and to signal that the present unscheduled service period is over. If the reserved buffer has only one frame of data buffered, it will transmit that frame of data, and likewise set the MOREDATA bit to indicate there is no more data if the aggregate buffer is empty, otherwise the unreserved data in the aggregate buffer will also be transmitted to the mobile station. In response to receiving the response frame, in the preferred embodiment, the mobile station transmits an acknowledgement 520 within a short interframe space time period 518. If the response frame indicated the end of the present unscheduled service period, the mobile station then places the WLAN subsystem into a low power state after receiving the response frame at time 522.
Referring now to FIG. 6, there is shown a flow chart diagram 600 illustrating a hybrid method of performing power save operation in a mobile station of a WLAN in accordance with the invention. At the start 602 of the method the mobile station and access point have negotiated a reserved traffic stream and established a schedule by which to exchange data for the reserved traffic stream and the mobile station has put its WLAN subsystem in low power mode until the beginning of a scheduled service period. At the occurrence of the beginning a scheduled service period, the mobile station commences powering up the WLAN subsystem (604) to begin the scheduled transaction (606). During the scheduled service period, the access point transmits reserved data to the mobile station, and identified the traffic stream with the unique traffic stream identifier. At the end of the scheduled service period, the access point still may have data left to transmit to the mobile station, and indicates such in a last frame transmitted to the mobile station. The access point may indicate detailed, per access category buffering information describing the access categories of information buffered at the access point. In IEEE 802.11 there are presently four access categories described, including voice, video, and best effort categories. During the scheduled service period the mobile station may transmit data to the access point as well. After the end of the scheduled transaction, the mobile station may place the WLAN subsystem back into a low power state (608). The mobile station then determines whether an unscheduled transaction is appropriate (610), such as by the detailed access category buffering information provided by the access point, for example. The mobile station may weigh various parameters, such as the present battery status of the mobile station, the type of data present at the access point, and so on. If the mobile station decides an unscheduled transaction is appropriate, the mobile station brings the WLAN subsystem out of low power mode to active mode (612), and initiates an unscheduled transaction (614) in accordance with the method shown and described in FIGS. 4–5. Once the unscheduled transaction is over, the mobile station again places the WLAN subsystem in low power mode (616). The mobile station the waits for the next scheduled service period (618) and repeats the process. Likewise, the mobile station had determined that an unscheduled transaction would not be appropriate (610), due to, for example, low battery power or the data at the access point is of low priority, the mobile station will skip the unscheduled transaction and wait for the next scheduled transaction (618).
Referring now to FIG. 7, there is shown a flow chart diagram of a mobile station frame exchange process during an unscheduled transaction, in accordance with the invention. At the start 700 the mobile station checks to see if there is data presently pending for the reserved traffic stream from the voice or other real time media processors. If not, then the mobile station waits as the polling window timer times a polling window. The mobile station also contends for the WLAN channel during this time. Once the channel is acquired, the mobile station transmits a polling frame (702). The polling frame will contain data if data was pending, otherwise the polling frame will be a null frame. The polling frame identifies the reserved traffic stream. The reserved traffic stream is preferably identified by its TSID, and the presence of the traffic stream identifier indicates to the access point that the mobile station is using an unscheduled transaction. In one embodiment of the invention, aggregate response from the access point is the default mode, but the aggregate response mode may also be selectable, and the desire to receive an aggregate response may be indicated in the polling frame.
In the preferred mode the access point transmits and acknowledgment which is received by the mobile station (703). If the acknowledgement is not received (704), the mobile station may back off by waiting, then retransmit the polling frame. After transmitting the polling frame, and, in the preferred mode, receiving the acknowledgment, the mobile station then waits for the access point to respond. Since the response is not scheduled, the time of the wait is variable, although the mobile station may have a preselected maximum time period to wait before undertaking an error procedure, assuming a failure of access point to respond. However, assuming normal operation, the access point will transmit an aggregation of response frames which will be received by the mobile station (706). In transmitting data from the aggregate buffer, data belonging to the traffic stream identified by the TSID used by the mobile station in the polling frame may be transmitted first, before unreserved data, in the aggregate response. Again, in the preferred mode, the mobile station will transmit an acknowledgement to assure the access point of a successful delivery. Upon receiving the response frame, the mobile station checks the EUSP bit to see if the UPSD service period is over. In the preferred embodiment, the MOREDATA bit may be used to signal when more date is coming from the access point (708), and when it is set it indicates that the service period is continuing until at least one more response frame is received. If the MOREDATA bit indicates subsequent frames are coming, then the mobile station remains active to receive them as it did for the first response frame. It is contemplated that subsequent response frames may contain data for a different reserved traffic stream also in use by the mobile station, or for the present reserved traffic stream. Once a response frame is received indicating no more data is coming from the access point, the process ends (710) and the mobile station places the WLAN subsystem in low power mode.
Referring now to FIG. 8, there is shown a flow chart diagram 800 of a method of buffering data at an access point, in accordance with the invention. At the start (802) of the method, the access point has admitted a reserved traffic stream for establishing a call to a mobile station. Data packets arrive from a network at the access point that are designated for the mobile station. As data packets arrive, the access point checks to see if the data packet is destined for a mobile station that is presently in a power save mode (804). If the mobile station for which an arriving packet is destined is not presently in a power save mode, the access point transmits the packet (806) to the mobile station. If the mobile station is presently in a power save mode, then the access point must determine whether the mobile station is using a legacy power save mode or the present unscheduled power save delivery mode (808). If the mobile station is using a legacy power save mode, then the access point buffers the packet in a unreserved buffer (810) and will signal the mobile station as to the state of its buffer in, for example, a periodic beacon frame transmitted by the access point. If the packet is associated with an admitted flow for a mobile station using power save mode, then the packet is stored in the reserved buffer (812).
Therefore the invention provides A method of performing power save operation in a wireless local area network (WLAN) by a mobile station in which a recurring service period schedule set up between the mobile station and an access point. The scheduled service periods occur at periodic intervals and are for maintaining a reserved traffic stream. The reserved traffic stream is identified by a reserved traffic stream identifier, and the mobile station has its WLAN subsystem initially in a low power mode. The method commences by powering up the WLAN subsystem of the mobile station and commencing a scheduled service period. At the end of the scheduled service period the mobile stations receives from the access point an indication that the access point has more data in a buffer of the access point for the mobile station. After receiving the last frame of the scheduled service period, the mobile station places the WLAN subsystem into low power mode. If the mobile station decides it is appropriate, the mobile station then commences initiating an unscheduled service period to retrieve the remaining data buffered at the access point for the mobile station. The unscheduled service period begins by powering up the WLAN subsystem and transmitting a polling frame to the access point. The polling frame includes the reserved traffic stream identifier. In response, the mobile station receives at least one response frame from the access point. At the conclusion of the unscheduled service period, the mobile station places the WLAN subsystem into low power mode. In one embodiment receiving the response frame includes receiving an aggregate response in which both reserved and unreserved data is received. The aggregate mode may be a default mode, or it may be triggered by transmitting the polling frame with an aggregation bit set.
The present method also prescribes a method of retrieving data from an access point by a mobile station in a wireless local area network (WLAN), where the reserved data corresponds to a reserved traffic stream and is identified by a reserved traffic stream identifier. The method includes performing a scheduled transaction between the mobile station and access point during a scheduled service period. The mobile station transitions from a low power WLAN mode to an active WLAN mode to commence the scheduled transaction, and then transitions from the active WLAN mode to a low power WLAN mode upon completion the scheduled transaction. After the scheduled transaction is complete. The mobile station commences performing an unscheduled transaction between the mobile station and access point during an unscheduled service period. The mobile station transitions from a low power WLAN mode to an active WLAN mode to initiate the unscheduled transaction, and then transitions from the active WLAN mode to a low power WLAN mode upon completing the unscheduled transaction. It is contemplated that the unscheduled transaction may be performed in response to the access point indicating at the end of the scheduled service period that the access point still has data for the mobile station, or, alternatively, the mobile station may have data to transmit to the access point. If the access point indicates at the end of the scheduled transaction that there is still data buffered at the access point, the access point may indicate the type of data, such as the access category of the data and whether the data is part of a reserved traffic stream. Data that is part of a reserved traffic stream may be part of a live voice call. The mobile station may decide whether or not to initiate an unscheduled service period by checking various parameters, such as, for example, battery power status, signal quality level, the priority of the data buffered at the access point, and so on.
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (13)

1. A method of performing power save operation in a wireless local area network (WLAN) by a mobile station, a recurring service period schedule set up between the mobile station and an access point including regularly scheduled service periods for a reserved traffic stream, the reserved traffic stream identified by a reserved traffic stream identifier, the mobile station having a WLAN subsystem that is initially in a low power mode, the method comprising:
powering up the WLAN subsystem of the mobile station;
commencing a scheduled service period;
receiving from the access point at the end of a scheduled service period an indication that the access point has more reserved data of a reserved traffic stream in a buffer of the access point at an end of the scheduled service period;
placing the WLAN subsystem into low power mode at the end of the scheduled service period
commencing an unscheduled service period to retrieve the remaining data buffered at the access point for the mobile station, comprising:
powering up the WLAN subsystem;
transmitting a polling frame to the access point, the polling frame including the reserved traffic stream identifier;
receiving at least one response frame from the access point in response to transmitting the polling frame; and
placing the WLAN subsystem into low power mode after receiving the at least one response frame.
2. A method of performing power save operation as defined in claim 1, wherein receiving at least one response frame comprises receiving at least one aggregate response frame.
3. A method of performing power save operation as defined by claim 2, wherein receiving the aggregate response frame is received in response to transmitting the polling frame with an aggregate bit set.
4. A method of performing power save operation as defined by claim 1, further comprising receiving an acknowledgement frame at the mobile station from the access point over the WLAN channel in response to transmitting the polling frame.
5. A method of performing power save operation as defined by claim 1, further comprising transmitting an acknowledgement frame from the mobile station to the access point over the WLAN channel in response to receiving the at least one response frame.
6. A method of performing power save operation as defined by claim 2, wherein:
receiving the at least one aggregate response frame includes receiving a header of a first frame of the aggregate response having a MOREDATA bit set to indicate a second response frame will be transmitted subsequently;
the method further comprising receiving a second response frame at the mobile station.
7. A method of performing power save operation as defined by claim 1, wherein transmitting the polling frame comprises transmitting a null frame.
8. A method of performing power save operation as defined by claim 1, further comprising acquiring the WLAN channel after waking up the WLAN subsystem, performed by contending for the WLAN channel.
9. A method of performing power save operation as defined by claim 8, wherein contending for the WLAN channel is performed by carrier sensing.
10. A method of retrieving data from an access point by a mobile station in a wireless local area network (WLAN), the reserved data corresponding to a reserved traffic stream and identified by a reserved traffic stream identifier, the method comprising:
performing a scheduled transaction between the mobile station and access point during a scheduled service period, the mobile station transitioning from a low power WLAN mode to an active WLAN mode to commence the scheduled transaction, and then transitioning from the active WLAN mode to a low power WLAN mode upon completion the scheduled transactions, wherein the access point indicates at the end of the scheduled transaction that the access point has buffered data for the mobile station that could not be delivered within the scheduled service period; and
performing an unscheduled transaction between the mobile station and access point during an unscheduled service period, the mobile station transitioning from a low power WLAN mode to an active WLAN mode to initiate the unscheduled transaction, and then transitioning from the active WLAN mode to a low power WLAN mode upon completing the unscheduled transaction, wherein performing the unscheduled transaction is performed in response to receiving the indication from the access point that the access point has buffered data for the mobile station that could not be delivered within the scheduled service period.
11. A method of retrieving reserved data from an access point by a mobile station as defined in claim 10, wherein the buffered data that could not be delivered during the scheduled service period is reserved data that belongs to a reserved traffic stream.
12. A method of retrieving reserved data from an access point by a mobile station as defined in claim 11, wherein the reserved data that could not be delivered during the scheduled service period is voice data, and wherein the reserved traffic stream is part of a live voice call.
13. A method of retrieving reserved data from an access point by a mobile station as defined in claim 10, further comprising checking a battery status of the mobile station before performing the unscheduled transaction, and commencing performing the scheduled only if the battery status indicates sufficient power budget is available to perform the unscheduled transaction.
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PCT/US2004/042325 WO2005064952A1 (en) 2003-12-19 2004-12-16 Hybrid power save delivery method in a wireless local area network for real time communication
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Cited By (47)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040081133A1 (en) * 2002-10-25 2004-04-29 Nattavut Smavatkul Method of communication device initiated frame exchange
US20040246970A1 (en) * 2003-06-06 2004-12-09 Alcatel Scheduling unit with optimized jitter and queue occupancy
US20050180367A1 (en) * 2004-02-06 2005-08-18 John Dooley Method and system for multiple basic and extended service set identifiers in wireless local area networks
US20050180425A1 (en) * 2004-02-13 2005-08-18 Nokia Corporation Protocol for indicating enhanced capabilities for use by short-range wireless connectivity equipment
US20050207400A1 (en) * 2004-03-16 2005-09-22 Masahito Shinohara Apparatus, system, and method for radio communications
US20050286446A1 (en) * 2004-04-01 2005-12-29 Devicescape Software Inc. Multi channel throughput enhancement
US20050289224A1 (en) * 2004-06-08 2005-12-29 Bose Corporation Managing an audio network
US20060025181A1 (en) * 2004-07-30 2006-02-02 Nokia Corporation System and method for managing a wireless connection to reduce power consumption of a mobile terminal
US20060153114A1 (en) * 2004-11-26 2006-07-13 Matsushita Electric Industrial Co., Ltd. Communication system, communication terminal, and communication method
US20060229023A1 (en) * 2005-03-31 2006-10-12 Intel Corporation Device, system and method for coordinating power saving with access categories
US20070026863A1 (en) * 2005-07-27 2007-02-01 Wilson Timothy J Method and apparatus to facilitate scanning in a wireless local area network
US20070047451A1 (en) * 2005-07-25 2007-03-01 Matsushita Electric Industrial Co., Ltd. HARQ process restriction and transmission of non-scheduled control data via uplink channels
US20070086414A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co., Ltd. Method for allocating transmission period in a wireless communication system
US20070143637A1 (en) * 2005-12-21 2007-06-21 Intel Corporation Power saving techniques for use in communication systems, networks, and devices
US20070230418A1 (en) * 2006-03-31 2007-10-04 Nokia Corporation Triggering rule for energy efficient data delivery
US20070238438A1 (en) * 2006-03-30 2007-10-11 Ayelet Alon Learning mechanism to configure power save parameters for automatic power save delivery
US20070260851A1 (en) * 2006-04-27 2007-11-08 Ali Taha Sleep optimization based on system information block scheduling
US20080070642A1 (en) * 2006-09-18 2008-03-20 Motorola, Inc. Method and system for consolidating power saving classes
US20080247377A1 (en) * 2007-04-06 2008-10-09 Peter Van Horn Independent medium access control for discovering wireless networks
US20080267118A1 (en) * 2007-04-27 2008-10-30 Zhijun Cai Uplink Scheduling and Resource Allocation With Fast Indication
US20080267168A1 (en) * 2007-04-27 2008-10-30 Zhijun Cai Slow Adaptation of Modulation and Coding for Packet Transmission
US20080310356A1 (en) * 2007-06-15 2008-12-18 Zhijun Cai System and Method for Large Packet Delivery During Semi-Persistently Allocated Session
US20080310400A1 (en) * 2007-06-15 2008-12-18 Research In Motion Limited System and Method for Link Adaptation Overhead Reduction
US20080310355A1 (en) * 2007-06-15 2008-12-18 Zhijun Cai System and Method for Semi-Persistent and Dynamic Scheduling and Discontinuous Reception Control
US20090046639A1 (en) * 2007-08-14 2009-02-19 Zhijun Cai System and Method for Handling Large IP Packets During VoIP Session
US20090052367A1 (en) * 2007-08-20 2009-02-26 Zhijun Cai System and Method for Retransmissions in a Discontinuous Reception Configured System
WO2009033253A1 (en) * 2007-09-14 2009-03-19 Research In Motion Limited System and method for discontinuous reception control start time
US20090215504A1 (en) * 2005-04-01 2009-08-27 Ixi Mobile (R &) Ltd. Content delivery system and method for a mobile communication device
US20090279449A1 (en) * 2008-05-07 2009-11-12 Nokia Corporation Quality of service and power aware forwarding rules for mesh points in wireless mesh networks
US20090310344A1 (en) * 2008-06-13 2009-12-17 Teco Image System Co., Ltd. Light projecting apparatus of scanner module and method for arranging light sources thereof
US7668128B1 (en) * 2004-05-17 2010-02-23 Avaya Inc. Features of power save in 802.11e wireless local area networks (WLANs)
CN101193444B (en) * 2006-11-30 2010-08-11 华为技术有限公司 Resource allocation method and its system and device
US20100316032A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Service Period Recovery wIth Source/Destination help
US20100315980A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Unified contention based period
US20100317388A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Personal Independent Basic Service Set Cluster Resource Sharing
US20110158209A1 (en) * 2009-12-30 2011-06-30 Motorola, Inc. Method and apparatus for updating presence state of a station in a wireless local area network (wlan)
US8144135B2 (en) 2001-10-19 2012-03-27 Research In Motion Limited Hand-held electronic device with multiple input mode thumbwheel
US8464149B2 (en) 1998-06-26 2013-06-11 Research In Motion Limited Hand-held electronic device with autopunctuation
US8477674B2 (en) 2008-03-12 2013-07-02 Nokia Corporation Wireless network including post groupcast time
US9134759B2 (en) 1998-06-26 2015-09-15 Blackberry Limited Dual-mode mobile communication device
US9326235B1 (en) * 2007-09-07 2016-04-26 Marvell International Ltd. Method and apparatus for wireless arbiter power saving
US9367141B2 (en) 1998-06-26 2016-06-14 Blackberry Limited Hand-held electronic device with a keyboard optimized for use with the thumbs
US10383069B2 (en) 2014-03-18 2019-08-13 Smartrek Technologies Inc. Mesh network system and techniques
US10484905B2 (en) 2015-01-26 2019-11-19 Apple Inc. Optimizing operation of constrained user equipment
US10856231B2 (en) 2010-07-26 2020-12-01 Seven Networks, Llc Optimizing mobile network traffic coordination across multiple applications running on a mobile device
US10959174B2 (en) 2017-09-02 2021-03-23 Apple Inc. Wake-up radio with urgent-data criterion
US11375453B2 (en) 2017-12-21 2022-06-28 Apple Inc. Power-efficient communication of group-addressed frames

Families Citing this family (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4386732B2 (en) 2002-01-08 2009-12-16 セブン ネットワークス, インコーポレイテッド Mobile network connection architecture
US7583648B2 (en) * 2003-05-08 2009-09-01 Meshdynamics, Inc. Managing latency and jitter on wireless LANs
US7603146B2 (en) * 2004-01-12 2009-10-13 Avaya Inc. Efficient power management in wireless local area networks
US20050215200A1 (en) * 2004-03-25 2005-09-29 General Motors Corporation Method and system for implementing a vehicle WiFi access point gateway
CA2504809C (en) * 2004-04-21 2012-07-10 Avaya Technology Corp. Organization of automatic power save delivery buffers at an access point
US20060056322A1 (en) * 2004-09-10 2006-03-16 Simpson Floyd D Method for updating a timer function in a mobile station in a wireless local area network
US7545783B2 (en) * 2004-09-27 2009-06-09 Siemens Communications, Inc. System and method for using presence to configure an access point
US7477616B2 (en) * 2005-01-31 2009-01-13 Symbol Technologies, Inc. Power saving frame transmission method
US20060253279A1 (en) * 2005-05-04 2006-11-09 Sung Chih-Ta S Method and apparatus of wireless audio playback system
US7912033B2 (en) * 2005-05-31 2011-03-22 Olympus Corporation Device synchronization on a communication network
DE102005040027B4 (en) * 2005-08-23 2012-10-25 Nec Europe Ltd. Method for controlling communication with mobile stations via a wireless network
US8755848B2 (en) * 2005-09-30 2014-06-17 Qualcomm Incorporated Mobile device power management
US7623545B2 (en) * 2005-10-14 2009-11-24 Menzo Wentink Method and apparatus for extended control over a wireless medium between two or more devices
CN101432781B (en) * 2005-12-20 2011-07-13 佐塞斯特转移股份有限责任公司 More power save multi-poll indication
US20070160027A1 (en) * 2005-12-27 2007-07-12 Muqattash Alaa H Dynamic power save modes
WO2007136435A2 (en) 2006-02-06 2007-11-29 Olympus Communication Technology Of America, Inc. Power management
US20070218938A1 (en) * 2006-03-20 2007-09-20 Conexant Systems, Inc. Sleep Mode Systems and Methods
JP4767746B2 (en) * 2006-04-21 2011-09-07 株式会社エヌ・ティ・ティ・ドコモ Packet scheduling method, base station and mobile station in mobile communication system
EP2037695A4 (en) * 2006-06-19 2013-02-06 Ntt Docomo Inc Radio resource allocation method and radio base station
US7860038B2 (en) * 2006-08-04 2010-12-28 Microsoft Corporation Wireless support for portable media player devices
US20080031208A1 (en) * 2006-08-04 2008-02-07 Microsoft Corporation Synchronization between wireless devices while saving power
US9596585B2 (en) * 2006-08-04 2017-03-14 Microsoft Technology Licensing, Llc Managing associations in ad hoc networks
JP5090455B2 (en) * 2006-09-14 2012-12-05 マーベル ワールド トレード リミテッド Ad hoc network power saving system and method
TWI329466B (en) * 2006-12-01 2010-08-21 Hon Hai Prec Ind Co Ltd Mobile station and method for verifying an access point thereof
US7650433B2 (en) * 2007-01-05 2010-01-19 Microsoft Corporation Power management for multi-interface device clusters
CN101222388B (en) 2007-01-12 2013-01-16 华为技术有限公司 Method and system for confirming existence of broadcast/multicast caching frame at access point
WO2008097060A2 (en) * 2007-02-09 2008-08-14 Lg Electronics Inc. Method for controlling power saving mode of ue in the mobile communication system
KR20080074696A (en) 2007-02-09 2008-08-13 엘지전자 주식회사 Method for controlling power saving mode in the mobile communication system
AU2012201089C1 (en) * 2007-06-15 2014-05-22 Blackberry Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
US20080310391A1 (en) * 2007-06-17 2008-12-18 Texas Instruments Incorporated Apparatus for and method of power save traffic control in client/server networks
US9002828B2 (en) 2007-12-13 2015-04-07 Seven Networks, Inc. Predictive content delivery
US8862657B2 (en) 2008-01-25 2014-10-14 Seven Networks, Inc. Policy based content service
US8570925B2 (en) * 2008-07-10 2013-10-29 Marvell World Trade Ltd. Systems and methods for reducing power consumption in wireless devices
EP2205029A1 (en) 2009-01-06 2010-07-07 Thomson Licensing A method for scheduling wake/sleep cycles by a central device in a wireless network
US8498230B2 (en) * 2009-03-03 2013-07-30 Nokia Corporation Power management in wireless communication systems
JP2011109252A (en) * 2009-11-13 2011-06-02 Canon Inc Communication device, control method of communication device, and program
US8838783B2 (en) 2010-07-26 2014-09-16 Seven Networks, Inc. Distributed caching for resource and mobile network traffic management
US9043433B2 (en) 2010-07-26 2015-05-26 Seven Networks, Inc. Mobile network traffic coordination across multiple applications
CN102457945A (en) * 2010-10-20 2012-05-16 鸿富锦精密工业(深圳)有限公司 Customer premise equipment and power-saving method for same
WO2012060995A2 (en) 2010-11-01 2012-05-10 Michael Luna Distributed caching in a wireless network of content delivered for a mobile application over a long-held request
US8843153B2 (en) 2010-11-01 2014-09-23 Seven Networks, Inc. Mobile traffic categorization and policy for network use optimization while preserving user experience
KR20130123430A (en) * 2011-03-07 2013-11-12 인텔 코포레이션 Grouped machine-to-machine communications
US9001720B2 (en) 2011-08-31 2015-04-07 Maarten Menzo Wentink Power save with data fetch time, with end of data indication, and with more data acknowledgement
WO2013129861A1 (en) * 2012-02-28 2013-09-06 엘지전자 주식회사 Method for setting service period in wireless communication system and apparatus for same
CN103369597B (en) * 2012-03-31 2018-11-09 中兴通讯股份有限公司 The sending method and device of radio frames
US8812695B2 (en) 2012-04-09 2014-08-19 Seven Networks, Inc. Method and system for management of a virtual network connection without heartbeat messages
KR20150023310A (en) 2012-04-30 2015-03-05 엘지전자 주식회사 Method and device for accessing channel in wireless lan system
GB2496235B (en) * 2012-07-16 2014-01-08 Renesas Mobile Corp Composite Poll and Data Message
US10057859B2 (en) * 2012-11-06 2018-08-21 Digi International Inc. Synchronized network for battery backup
KR102091138B1 (en) * 2013-09-12 2020-03-19 삼성전자주식회사 Method for Data Transmission for Wireless Network Environment and Data Transmitter
KR102137962B1 (en) * 2014-01-20 2020-07-27 삼성전자 주식회사 Method and apparatus supporting IP multimedia subsystem
JP6313460B2 (en) * 2014-02-04 2018-04-18 エルジー エレクトロニクス インコーポレイティド Operation method and apparatus based on power save mode in wireless LAN
US10200951B2 (en) * 2014-02-20 2019-02-05 Qualcomm Incorporated Low power low latency protocol for data exchange
CN105101361B (en) 2014-04-25 2018-08-03 鸿富锦精密工业(深圳)有限公司 Node apparatus and its communication means
WO2020243117A1 (en) * 2019-05-24 2020-12-03 Marvell Asia Pte, Ltd. Power save and group-addressed frames in wlan using multiple communication links

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5940771A (en) * 1991-05-13 1999-08-17 Norand Corporation Network supporting roaming, sleeping terminals
US6023621A (en) * 1996-06-28 2000-02-08 Harris Corporation Wireless communications system and method having dynamic reallocation of communication frequencies
US6404751B1 (en) * 1998-09-15 2002-06-11 Crisco Technology, Inc. Common control channel dynamic frequency assignment method and protocol
US20030152059A1 (en) * 2002-01-22 2003-08-14 Odman Knut T. System and method for handling asynchronous data in a wireless network
US20040042435A1 (en) * 2002-09-04 2004-03-04 Koninklijke Philips Electronics N.V. Apparatus and method for providing QoS service schedule and bandwidth allocation to a wireless station
US20040131019A1 (en) * 2003-01-08 2004-07-08 Sharp Laboratories Of America, Inc. System and method for synchronizing an IEEE 802.11 power-save interval
US20050135318A1 (en) * 2003-10-15 2005-06-23 Qualcomm Incorporated High speed media access control with legacy system interoperability

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000307601A (en) * 1999-04-23 2000-11-02 Sony Corp Method and device for radio transmission
JP3705034B2 (en) * 1999-09-01 2005-10-12 ソニー株式会社 Wireless transmission control method and wireless transmission device
JP4444660B2 (en) * 2002-01-22 2010-03-31 フリースケール セミコンダクター インコーポレイテッド System and method for handling long asynchronous data in asynchronous time slots

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5940771A (en) * 1991-05-13 1999-08-17 Norand Corporation Network supporting roaming, sleeping terminals
US6023621A (en) * 1996-06-28 2000-02-08 Harris Corporation Wireless communications system and method having dynamic reallocation of communication frequencies
US6404751B1 (en) * 1998-09-15 2002-06-11 Crisco Technology, Inc. Common control channel dynamic frequency assignment method and protocol
US20030152059A1 (en) * 2002-01-22 2003-08-14 Odman Knut T. System and method for handling asynchronous data in a wireless network
US20040042435A1 (en) * 2002-09-04 2004-03-04 Koninklijke Philips Electronics N.V. Apparatus and method for providing QoS service schedule and bandwidth allocation to a wireless station
US20040131019A1 (en) * 2003-01-08 2004-07-08 Sharp Laboratories Of America, Inc. System and method for synchronizing an IEEE 802.11 power-save interval
US20050135318A1 (en) * 2003-10-15 2005-06-23 Qualcomm Incorporated High speed media access control with legacy system interoperability

Cited By (109)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8464149B2 (en) 1998-06-26 2013-06-11 Research In Motion Limited Hand-held electronic device with autopunctuation
US8493322B2 (en) 1998-06-26 2013-07-23 Research In Motion Limited Hand-held electronic device
US9134759B2 (en) 1998-06-26 2015-09-15 Blackberry Limited Dual-mode mobile communication device
US9367141B2 (en) 1998-06-26 2016-06-14 Blackberry Limited Hand-held electronic device with a keyboard optimized for use with the thumbs
US9703390B2 (en) 1998-06-26 2017-07-11 Blackberry Limited Hand-held electronic device
US10067572B2 (en) 1998-06-26 2018-09-04 Blackberry Limited Hand-held electronic device
US8144135B2 (en) 2001-10-19 2012-03-27 Research In Motion Limited Hand-held electronic device with multiple input mode thumbwheel
US7590079B2 (en) * 2002-10-25 2009-09-15 Motorola, Inc. Method of communication device initiated frame exchange
US20040081133A1 (en) * 2002-10-25 2004-04-29 Nattavut Smavatkul Method of communication device initiated frame exchange
US7400631B2 (en) * 2003-06-06 2008-07-15 Alcatel Scheduling unit with optimized jitter and queue occupancy
US20040246970A1 (en) * 2003-06-06 2004-12-09 Alcatel Scheduling unit with optimized jitter and queue occupancy
US7492744B2 (en) 2004-02-06 2009-02-17 Symbol Technologies, Inc. Method and system for multiple basic and extended service set identifiers in wireless local area networks
US20050180367A1 (en) * 2004-02-06 2005-08-18 John Dooley Method and system for multiple basic and extended service set identifiers in wireless local area networks
US7760671B2 (en) 2004-02-13 2010-07-20 Nokia Corporation Protocol for indicating enhanced capabilities for use by short-range wireless connectivity equipment
US20050180425A1 (en) * 2004-02-13 2005-08-18 Nokia Corporation Protocol for indicating enhanced capabilities for use by short-range wireless connectivity equipment
US20050207400A1 (en) * 2004-03-16 2005-09-22 Masahito Shinohara Apparatus, system, and method for radio communications
US20050286446A1 (en) * 2004-04-01 2005-12-29 Devicescape Software Inc. Multi channel throughput enhancement
WO2005109929A3 (en) * 2004-05-04 2006-11-09 Symbol Technologies Inc Method and system for multiple basic and extended service set identifiers in wireless local area networks
US7668128B1 (en) * 2004-05-17 2010-02-23 Avaya Inc. Features of power save in 802.11e wireless local area networks (WLANs)
US8214447B2 (en) * 2004-06-08 2012-07-03 Bose Corporation Managing an audio network
US20050289224A1 (en) * 2004-06-08 2005-12-29 Bose Corporation Managing an audio network
US7764981B2 (en) * 2004-07-30 2010-07-27 Nokia Corporation System and method for managing a wireless connection to reduce power consumption of a mobile terminal
US20060025181A1 (en) * 2004-07-30 2006-02-02 Nokia Corporation System and method for managing a wireless connection to reduce power consumption of a mobile terminal
US7855986B2 (en) * 2004-11-26 2010-12-21 Panasonic Corporation Communication terminal and method for handling power off time
US20060153114A1 (en) * 2004-11-26 2006-07-13 Matsushita Electric Industrial Co., Ltd. Communication system, communication terminal, and communication method
US20060229023A1 (en) * 2005-03-31 2006-10-12 Intel Corporation Device, system and method for coordinating power saving with access categories
US7577113B2 (en) * 2005-03-31 2009-08-18 Intel Corporation Device, system and method for coordinating power saving with access categories
US20090215504A1 (en) * 2005-04-01 2009-08-27 Ixi Mobile (R &) Ltd. Content delivery system and method for a mobile communication device
US8259693B2 (en) 2005-07-25 2012-09-04 Panasonic Corporation HARQ process restriction and transmission of non-scheduled control data via uplink channels
US7447504B2 (en) * 2005-07-25 2008-11-04 Matsushita Electric Industrial Co., Ltd. HARQ process restriction and transmission of non-scheduled control data via uplink channels
US20070047451A1 (en) * 2005-07-25 2007-03-01 Matsushita Electric Industrial Co., Ltd. HARQ process restriction and transmission of non-scheduled control data via uplink channels
US20090034487A1 (en) * 2005-07-25 2009-02-05 Matsushita Electric Industrial Co., Ltd. Harq process restriction and transmission of non-scheduled control data via uplink channels
US20070026863A1 (en) * 2005-07-27 2007-02-01 Wilson Timothy J Method and apparatus to facilitate scanning in a wireless local area network
WO2007018713A2 (en) * 2005-07-27 2007-02-15 Motorola, Inc. Method and apparatus to facilitate scanning in a wireless local area network
WO2007018713A3 (en) * 2005-07-27 2007-05-03 Motorola Inc Method and apparatus to facilitate scanning in a wireless local area network
US20070086415A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co. Ltd. Apparatus for allocating transmission period in a wireless communication system
US7688831B2 (en) * 2005-10-18 2010-03-30 Samsung Electronics Co., Ltd. Wireless communication system for allocating transmission period
US7688767B2 (en) * 2005-10-18 2010-03-30 Samsung Electronics Co., Ltd. Apparatus for allocating transmission period in a wireless communication system
US7701888B2 (en) * 2005-10-18 2010-04-20 Samsung Electronics Co., Ltd. Apparatus for allocating transmission period in a wireless communication system
US20070086413A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co., Ltd. Apparatus for allocating transmission period in a wireless communication system
US20070086417A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co., Ltd. Wireless communication system for allocating transmission period
US20070086416A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co., Ltd. Method for allocating transmission period in a wireless communication system
US20070086414A1 (en) * 2005-10-18 2007-04-19 Samsung Electronics Co., Ltd. Method for allocating transmission period in a wireless communication system
US7660274B2 (en) * 2005-10-18 2010-02-09 Samsung Electronics Co., Ltd. Method for allocating transmission period in a wireless communication system
US7656832B2 (en) * 2005-10-18 2010-02-02 Samsung Electronics Co., Ltd. Method for allocating transmission period in a wireless communication system
US20070143637A1 (en) * 2005-12-21 2007-06-21 Intel Corporation Power saving techniques for use in communication systems, networks, and devices
US7500119B2 (en) * 2005-12-21 2009-03-03 Intel Corporation Power saving techniques for use in communication systems, networks, and devices
US20070238438A1 (en) * 2006-03-30 2007-10-11 Ayelet Alon Learning mechanism to configure power save parameters for automatic power save delivery
US7668129B2 (en) 2006-03-30 2010-02-23 Intel Corporation Learning mechanism to configure power save parameters for automatic power save delivery
US20070230418A1 (en) * 2006-03-31 2007-10-04 Nokia Corporation Triggering rule for energy efficient data delivery
US8185726B2 (en) 2006-04-27 2012-05-22 Qualcomm Incorporated Sleep optimization based on system information block scheduling
US20070260851A1 (en) * 2006-04-27 2007-11-08 Ali Taha Sleep optimization based on system information block scheduling
US7426404B2 (en) 2006-09-18 2008-09-16 Motorola, Inc. Method and system for consolidating power saving classes
US20080070642A1 (en) * 2006-09-18 2008-03-20 Motorola, Inc. Method and system for consolidating power saving classes
CN101193444B (en) * 2006-11-30 2010-08-11 华为技术有限公司 Resource allocation method and its system and device
US20080247377A1 (en) * 2007-04-06 2008-10-09 Peter Van Horn Independent medium access control for discovering wireless networks
US8064390B2 (en) 2007-04-27 2011-11-22 Research In Motion Limited Uplink scheduling and resource allocation with fast indication
US8213930B2 (en) 2007-04-27 2012-07-03 Research In Motion Limited Uplink scheduling and resource allocation with fast indication
US20080267118A1 (en) * 2007-04-27 2008-10-30 Zhijun Cai Uplink Scheduling and Resource Allocation With Fast Indication
US8204508B2 (en) 2007-04-27 2012-06-19 Research In Motion Limited Uplink scheduling and resource allocation with fast indication
US20080267168A1 (en) * 2007-04-27 2008-10-30 Zhijun Cai Slow Adaptation of Modulation and Coding for Packet Transmission
US8472397B2 (en) 2007-04-27 2013-06-25 Research In Motion Limited Uplink scheduling and resource allocation with fast indication
WO2008131530A1 (en) * 2007-04-27 2008-11-06 Research In Motion Limited Uplink scheduling and resource allocation with fast indication
US8964650B2 (en) 2007-06-15 2015-02-24 Blackberry Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
US20080310355A1 (en) * 2007-06-15 2008-12-18 Zhijun Cai System and Method for Semi-Persistent and Dynamic Scheduling and Discontinuous Reception Control
WO2008151411A1 (en) * 2007-06-15 2008-12-18 Research In Motion Limited System and method for large packet delivery during semi persistently allocated session
US20080310356A1 (en) * 2007-06-15 2008-12-18 Zhijun Cai System and Method for Large Packet Delivery During Semi-Persistently Allocated Session
US9467979B2 (en) 2007-06-15 2016-10-11 Blackberry Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
US20080310400A1 (en) * 2007-06-15 2008-12-18 Research In Motion Limited System and Method for Link Adaptation Overhead Reduction
US8432818B2 (en) 2007-06-15 2013-04-30 Research In Motion Limited System and method for link adaptation overhead reduction
US9854522B2 (en) 2007-06-15 2017-12-26 Blackberry Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
WO2008151407A1 (en) * 2007-06-15 2008-12-18 Research In Motion Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
US10349349B2 (en) 2007-06-15 2019-07-09 Blackberry Limited System and method for semi-persistent and dynamic scheduling and discontinuous reception control
US20090046639A1 (en) * 2007-08-14 2009-02-19 Zhijun Cai System and Method for Handling Large IP Packets During VoIP Session
US20090054006A1 (en) * 2007-08-20 2009-02-26 Zhijun Cai System and Method for DRX Control and NACK/ACK
US10701614B2 (en) 2007-08-20 2020-06-30 Blackberry Limited System and method for DRX control and NACK/ACK
US8369256B2 (en) 2007-08-20 2013-02-05 Research In Motion Limited Inactivity timer in a discontinuous reception configured system
US10212638B2 (en) 2007-08-20 2019-02-19 Blackberry Limited System and method for DRX control and NACK/ACK
US8144679B2 (en) 2007-08-20 2012-03-27 Research In Motion Limited Inactivity timer in a discontinuous reception configured system
US20090052367A1 (en) * 2007-08-20 2009-02-26 Zhijun Cai System and Method for Retransmissions in a Discontinuous Reception Configured System
US8265080B2 (en) 2007-08-20 2012-09-11 Motorola Mobility Llc System and method for retransmissions in a discontinuous reception configured system
US8483624B2 (en) 2007-08-20 2013-07-09 Research In Motion Limited System and method for DRX control and NACK/ACK
US20090052361A1 (en) * 2007-08-20 2009-02-26 Zhijun Cai Inactivity Timer in a Discontinuous Reception Configured System
US9019884B2 (en) 2007-08-20 2015-04-28 Blackberry Limited Inactivity timer in a discontinuous reception configured system
US8699393B2 (en) 2007-08-20 2014-04-15 Blackberry Limited Inactivity timer in a discontinuous reception configured system
US9326235B1 (en) * 2007-09-07 2016-04-26 Marvell International Ltd. Method and apparatus for wireless arbiter power saving
US20090073907A1 (en) * 2007-09-14 2009-03-19 Zhijun Cai System and Method for Discontinuous Reception Control Start Time
WO2009033253A1 (en) * 2007-09-14 2009-03-19 Research In Motion Limited System and method for discontinuous reception control start time
US8897192B2 (en) 2007-09-14 2014-11-25 Blackberry Limited System and method for discontinuous reception control start time
US8711745B2 (en) 2007-09-14 2014-04-29 Blackberry Limited System and method for discontinuous reception control start time
US9030986B2 (en) 2007-09-14 2015-05-12 Blackberry Limited System and method for discontinuous reception control start time
US8811250B2 (en) 2007-09-14 2014-08-19 Blackberry Limited System and method for discontinuous reception control start time
US8477674B2 (en) 2008-03-12 2013-07-02 Nokia Corporation Wireless network including post groupcast time
US8274894B2 (en) * 2008-05-07 2012-09-25 Nokia Corporation Quality of service and power aware forwarding rules for mesh points in wireless mesh networks
US20090279449A1 (en) * 2008-05-07 2009-11-12 Nokia Corporation Quality of service and power aware forwarding rules for mesh points in wireless mesh networks
US20090310344A1 (en) * 2008-06-13 2009-12-17 Teco Image System Co., Ltd. Light projecting apparatus of scanner module and method for arranging light sources thereof
US20100317388A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Personal Independent Basic Service Set Cluster Resource Sharing
US20100316032A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Service Period Recovery wIth Source/Destination help
US20100315980A1 (en) * 2009-06-10 2010-12-16 Stmicroelectronics, Inc. Unified contention based period
US8553714B2 (en) 2009-06-10 2013-10-08 Stmicroelectronics, Inc. Unified contention based period
US20110158209A1 (en) * 2009-12-30 2011-06-30 Motorola, Inc. Method and apparatus for updating presence state of a station in a wireless local area network (wlan)
US8660101B2 (en) * 2009-12-30 2014-02-25 Motorola Solutions, Inc. Method and apparatus for updating presence state of a station in a wireless local area network (WLAN)
US10856231B2 (en) 2010-07-26 2020-12-01 Seven Networks, Llc Optimizing mobile network traffic coordination across multiple applications running on a mobile device
US10383069B2 (en) 2014-03-18 2019-08-13 Smartrek Technologies Inc. Mesh network system and techniques
US11191045B2 (en) 2014-03-18 2021-11-30 Smartrek Technologies Inc. Mesh network system and techniques
US10484905B2 (en) 2015-01-26 2019-11-19 Apple Inc. Optimizing operation of constrained user equipment
US10959174B2 (en) 2017-09-02 2021-03-23 Apple Inc. Wake-up radio with urgent-data criterion
US11375453B2 (en) 2017-12-21 2022-06-28 Apple Inc. Power-efficient communication of group-addressed frames
US11895589B2 (en) 2017-12-21 2024-02-06 Apple Inc. Power-efficient communication of group-addressed frames

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